Hello, friend!
If the ONT is restored to factory settings, the related parameters need to be reconfigured.
In the case of an enterprise network, you need to re-deliver the corresponding configuration parameters through the OLT, and then log in to the ONT WebUI to set the parameters.
In the case of a home network, you need to contact the ISP to remotely restore the ONT online and deliver related parameters to the ONT.
Thanks!